docs: def pretty_print(self):
          """Use `PrettyTable` to perform formatted outprint."""
          pt = PrettyTable()
          if len(self) == 0:
              pt._set_field_names(['Sorry,'])
              pt.add_row([TRAIN_NOT_FOUND])
          else:
              pt._set_field_names(self.headers)
              for train in self.trains:
                  pt.add_row(train)
          print(pt)